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Biomedical subjects

C Bischoff

Publications and source records attributed to C Bischoff.

At least 55 records · Page 3Linked to original sources
PubMed1992

Competitive and non-competitive NMDA receptor antagonists in spatial learning tasks.

The effects of the competitive N-methyl-D-aspartate (NMDA) receptor antagonists, CGP37849 (3 or 6 mg/kg i.p.) and its ethyl ester CGP39551 (5 or 15 mg/kg i.p.) and of the non-competitive NMDA receptor antagonist, dizocilpine (0.16 mg/kg; i.p.) on acquisition by rats of different spatial orientation tasks in an 8-arm radial maze were evaluated. Neither of the CGP compounds influenced locomotor activity during spontaneous alternation, only dizocilpine increased the number of arm entries (locomotion). Preferred angles between consecutive arm entries were changed by the high doses of CGP37849 (6 mg/kg), CGP39551 (15 mg/kg) and dizocilpine (0.16 mg/kg). The high doses of both CGP compounds as well as dizocilpine produced impairments in the acquisition of an egocentric orientation task and an allocentric reversal task indicated by an increased number of arm entries and re-entries. Such amnesic effects did not occur after administration of low doses of CGP37849 (3 mg/kg) and CGP39551 (5 mg/kg), doses which are sufficient to produce anticonvulsant and anticataleptic effects. In contrast, the non-competitive NMDA receptor antagonist, dizocilpine, produced amnesic effects over the entire behaviourally effective dose range.

2-Amino-5-phosphonovalerate↗
PubMed1992

Motor responses evoked by magnetic brain stimulation in psychogenic limb weakness: diagnostic value and limitations.

The latencies and amplitudes of responses evoked by magnetic brain stimulation (magnetic evoked potentials, MEP) in the first dorsal interosseus and the anterior tibial (TA) muscles were investigated in 15 patients with psychogenic limb weakness and in 50 patients with limb weakness due to established organic central nervous system disease. Of the patients with psychogenic limb weakness, 3 presented with upper limb monopareses, 2 with lower limb monoparesis, 4 with hemipareses, 4 with parapareses and 2 with paraparesis. All patients with psychogenic weakness had MEP in arm and leg muscles with latencies within the normal range. MEP amplitudes were also normal except for 1 patient in whom the response amplitude in the TA of the plegic limb was reduced. In patients with limb weakness due to established organic disease, MEP were frequently but not invariably abnormal. In patients with plegic (i.e. completely paretic, MRC grade 0) muscles due to organic disease, MEP always were clearly abnormal. Normal MEP were sometimes elicited from paretic muscles, more commonly in association with cerebral hemisphere lesions than with spinal lesions. We conclude that psychogenic limb weakness is associated with normal MEP. However, normal MEP in mildly paretic muscles do not definitely exclude organic pathology.

Adolescent↗
PubMed1992

Motor responses evoked by magnetic brain stimulation in Huntington's disease.

In 34 patients with manifest Huntington's disease (HD), and in 21 first-degree offspring without clinical signs or symptoms, the sizes, central motor latencies (CMLs) and variation in latencies of EMG responses (MEPs) following transcranial magnetic brain stimulation were studied in muscles of the upper and lower extremities. In subgroups of patients and their offspring median and tibial nerve somatosensory evoked potentials (SEPs) and electrically elicited long-loop reflexes (LLRs) in hand muscles were also investigated. Increased MEP thresholds were observed in 10% of the HD offspring, while CML, latency variability and MEP amplitudes always lay within normal range. In contrast, SEPs were abnormal in 33%. In HD patients MEPs were found to be abnormal in up to 72% of patients when all available response parameters were taken into consideration. MEP abnormalities correlated with the duration of motor symptoms and the severity of choreic motor activity. When both MEPs and SEPs were evaluated, abnormalities could be detected in 91% of all HD patients. We suggest that abnormal MEPs might reflect an altered excitability of the cortico-spinal system as a consequence of basal ganglia dysfunction, rather than a structural damage of the investigated descending pathways. To localize the pathological mechanism responsible for altered LLRs, a "loop analysis" was performed by recording LLRs, MEPs and SEPs in the same patients. Alterations of LLRs correlated best with abnormal SEPs and might therefore be explained by reduced somatosensory input to the motor cortex.

Adolescent↗
PubMed1992

Increased F-wave duration in patients with spasticity.

F-wave responses of the posterior tibial nerve have been studied in 22 patients with spasticity and in 18 normal control subjects with surface EMG. Mean amplitude and mean duration of the F-waves were significantly (p less than 0.001) longer in patients with spasticity than in healthy controls. These findings could be the result of an enhanced spinal excitability in spasticity. Based on the present results F-wave recording may be used as a simple and practical technique for detection and documentation of spasticity.

Adult↗
PubMed1991

Do brief bursts of spike and wave activity cause a cerebral hyper- or hypoperfusion in man?

The correlation between brain activity and cerebral blood flow velocities during brief bursts of generalized spike and wave activity was analysed by simultaneous registration of the EEG and the intracranial flow patterns. The flow patterns of the middle cerebral artery were continuously recorded by means of transcranial Doppler ultrasonography using a specially developed monitoring system. A total of 25 bursts was investigated in 3 patients with spontaneous occurrence of generalized 3 Hz spike and wave activity and normal background EEG. Characteristic changes of the flow patterns were found in all cases: 3.41 +/- 0.98 s (n = 25) after the beginning of generalized spike and wave patterns, the flow velocity decreased by 25.84 +/- 10.45% (n = 25) below the 'preictal' flow velocity level. The period of flow velocity changes lasted several times longer than the phase of spike and wave activity.

Adult↗
PubMed1991

Abnormal conduction in corticospinal pathways in Wilson's disease: investigation of nine cases with magnetic brain stimulation.

Electromyographic (EMG) responses evoked by transcranial magnetic brain stimulation were studied in nine patients with Wilson's disease (WD). Six of the nine patients had prolonged central motor latencies (CMLs), reduced amplitude, or absent responses in at least one of the examined muscles. In one patient, abnormal EMG responses normalized following treatment with penicillamine. Pathophysiologically abnormal EMG responses might result from a potentially reversible impairment of corticomotoneuronal pathways and/or a reduced excitability of motoneurons due to basal ganglia dysfunction. The possible pathophysiological mechanisms are discussed.

Adult↗
PubMed1991

Is there an age-dependent continuous increase in the duration of the motor unit action potential?

The duration of the motor unit potential plays an important role in the diagnosis of neuromuscular diseases, but is also subject to physiological variations. In order to evaluate the age-related changes the mean motor unit potential duration was studied in 4 proximal and distal muscles of the upper and lower extremities in 111 healthy subjects between 20 and 80 years. Contrary to the results of previous researches no marked increase of mean duration could be found in subjects younger than 55 years. Subjects older than 55 showed a slight tendency towards increased duration of the motor unit potential. These findings are interpreted as the result of changes in fiber density and are in accordance with single fiber EMG records.

Action Potentials↗
PubMed1991

Obturator nerve injuries during intra-abdominal surgery.

Selective obturatory nerve lesions are described to occur relatively infrequent. In the present paper two patients developing signs and symptoms of an obturatory neuropathy as a result of abdominal surgery were reported. In a 48-year-old woman a bilateral obturator neuropathy occurred after bilateral ovarectomy with a weakness of the adductor muscles, typical electromyographic findings and sensory deficits in the medial aspect of the thigh. Similar unilateral signs and symptoms were seen in a 65-years-old man as a result of an aortofemoral bypass operation. Symptomatology and differential diagnosis of obturator nerve lesions are discussed.

Abdomen↗
PubMed1991

Lack of hyperlipidemia in carpal tunnel syndrome.

115 females with a definitive diagnosis of a carpal tunnel syndrome (CTS) are compared with a corresponding age-matched group of healthy females with regard to their lipidemic parameters. The incidence of hyperlipoproteinemias in CTS patients was equal to that in the control group so that hyperlipoproteinemia is unlikely to be a probable cause of the entrapment syndrome. A statistically significant increase in the level of alpha-lipoprotein (high-density lipoprotein) was found which cannot be readily explained.

Adult↗
PubMed1991

Cerebral vasospasm evaluated by transcranial Doppler ultrasonography at different intracranial pressures.

The present study evaluates the interdependence of clinical stage, cerebral vasospasm, intracranial pressure (ICP), and transcranial Doppler ultrasonographic parameters. The mean flow velocity of blood in the middle cerebral artery and the index of cerebral circulatory resistance as a measure of the peripheral vascular flow resistance were determined in 76 patients with spontaneous subarachnoid hemorrhage. The ICP was measured using an epidural transducer in 41 patients. There was no case in which both high ICP and a high mean flow velocity were observed simultaneously. The investigations led to the following conclusions. 1) In patients with a resistance index of less than 0.5, changes in the mean flow velocity seem to reflect sufficiently the actual severity and time course of vasospasm. 2) During the time course of vasospasm, an increase in the resistance index above values of 0.6 with a simultaneously decreased mean flow velocity indicates a rise in ICP rather than a reduction in vasospasm. 3) With a pronounced increase in ICP, evaluation of the severity and time course of vasospasm by transcranial Doppler ultrasonography based solely upon the mean flow velocity can lead to false-negative results.

Adult↗
PubMed1990

[Postinfectious myopathy. An important differential diagnosis in muscle pain].

Following a viral infection of the upper respiratory tract a 63-year-old woman developed a postinfectious myopathy with nonprogressive muscle weakness and diffuse muscle pain. Electromyography revealed typical changes of a myopathy with low-amplitude, splintered voluntary potentials and prematurely dense interference pattern, without additional abnormal spontaneous activity as a pointer to an acute inflammatory process. Muscle biopsy showed moderate focal atrophic and inflammatory changes but no perivascular inflammation. The clinical and biochemical tests were noncontributory and there was no evidence for collagen disease. No cortisone was given because of the minor degree of the postinfectious myopathy. The symptoms completely regressed within ten months.

Biopsy↗
PubMed1990

MK-801-induced stereotypy and its antagonism by neuroleptic drugs.

MK-801 [(+)-5-methyl-10,11-dihydroxy-5H-dibenzo-(a,d)cyclohepten-5,10-imi ne hydrogen maleate], which blocks glutamatergic transmission at the NMDA-receptor-gated ion channel, induced stereotypies which are similar to those found after intrastriatal injections of AP-5, e.g. sniffing and locomotion. Tests in familiar or unfamiliar environment (non-stressful or stressful situation) did not qualitatively change MK-801-induced effects. Haloperidol (0.1 mg/kg, IP) delayed the onset and shortened the duration of MK-801 (0.16; 0.33 mg/kg, IP)-induced stereotypy whereas clozapine (5 mg/kg, SC) potently antagonized it. However, exact quantification of sniffing, measured in an experimental chamber designed for this purpose, revealed an antagonism by both drugs, haloperidol as well as clozapine. Stereotypy is considered to represent an animal model of schizophrenia, and the antagonism of stereotypy with classical (haloperidol) as well as with atypical (clozapine) antipsychotic drugs is in accordance with the glutamate hypothesis of schizophrenia.

Animals↗
PubMed1990

[Extensive, continuous fasciculations of the lower leg as an isolated symptom--a clinical and electromyography follow-up].

10 patients suffering from a widespread continuous fasciculation of the lower extremities without any other neurological signs and symptoms are presented. A follow up study of 6 of these patients could be done. The fasciculation potentials were polyphasic with changing shape from discharge to discharge and appeared irregularly in most of the muscles of the legs. In 5 patients no change of clinical and neurophysiological signs could be detected over the period of observation, whereas in one patient a sensory polyneuropathy was evident in course of time. The findings illustrate that a state of widespread continuous fasciculations without other signs and symptoms is not predicative for the development of a amyotrophic lateral sclerosis.

Adult↗
PubMed1989

Decay and recovery of the stapedial reflex by prolonged stimulation in the diagnosis of myasthenia gravis.

The decay and recovery of stapedial reflex amplitude was investigated in 19 patients with myasthenia gravis and 30 control subjects. In 9 untreated patients the amplitude was reduced to less than 10% of the initial amplitude following continuous stimulation for 120 s, whereas the maximum decay in the control subjects was only 50%. In the group of treated patients the reflex decay showed individual variations. The rate of recovery after prolonged stimulation (5 min) was slower in the patient group, especially within the first 30 s of recovery. With increasing age, the rate of decay rose in the patient group as well as in the control group. The technical parameters necessary for obtaining information of clear diagnostic value are indicated, with which it was shown that the continuous prolonged stimulation of the stapedial muscle is a practical and valid method for the evaluation of patients with myasthenia gravis.

Adolescent↗
PubMed1989

[Colloid cysts of the 3d ventricle: problems of early intravital diagnosis].

Basing on two own cases with acute signs of increased obstructive intracranial pressure the problem of early diagnosis of colloid cysts of the third ventricle is discussed with special reference to case reports in the literature. In the absence of typical clinical signs and symptoms, there are acute and chronic constellations of signs and symptoms that point to a suspicion of an obstruction of liquor flow by a colloid cyst. It is explained which importance CT and MR assume in the diagnosis of these benign tumours that present a very varied neurological pattern. Special reference is made to the presentation of neuroradiological differential diagnoses and the application of specific examination methods, such as tomography in very thin layers and allowing some time to elapse after contrast medium administration has been effected.

Adult↗